toddlers biting and hitting

Hello,in here once again!!I hope someones got some advice as I really dont know what to do,I have a 13 month old little girl and I dont have many friends with children around her age but I have met a Lady because we do swimmig each week together who has a little girl the same age,well lately aswell as swimming weve been letting the girls have a little play date together but each time its been at her place.so my problem is the other little girl keeps hitting and biting mine!!Its really bad,I swear im not being an over protective mother but she does it as soon as I put her down she will just crawl up and hit or bite her and anything she has in her hands(last time it was quite a heavy plastic phone)no joke slamming it hard into her head!She had a bruise and scratches when we left because the whole time she just kept hitting and biting and scracthing,so I just dont know what to do!!I'd really like to continue the friendship but I dont want my DD to start copying her behaviour thinking its ok because shes so gentle usually like she doesnt hit back or anything she just sits and takes it!So Im ttrying to stop her doing it but her mum doesnt really say much,if it gets too bad again as it has been each time I will have to stop them playing which will be sad.Is this normal like i wondered if its a territory thing because we are at her place and her toys etc?I just dont know how to stop it,i dont want to upset them!!Any ideas??

It can be hard at that age as they really have no concept of hurting. It probably is a territorial thing, does the other child do the same thing when you are at a neutral place? Maybe you could try to have play dates at a park or somewhere neither child 'owns'.

If that were my child being hurt and the other parent wasn't / or didn't know what to say. I would pick up my child out of harms way and tell the other child (in a very calm reassuring voice) that they need to be gentle. I would also try and make sure I was close by, perhaps even sitting on the floor with them so that I could stop events happening before they got to that point.

Goodluck, sometimes its as much about sorting out the politics of what you should and shouldn't say to another parent or their child, as it is the behavior.